mysql怎么生成不重复的随机数

MySql数据库随机函授Rand()可以产生0~1之间带小数的随机数，只要将括号中的参数留空，所产生的数是完全随机的，出现重复的几率不大，但是不可避免会有重复的可能，如果需要完全避免重复，可以先用随机函数产生一堆数字，然后用剔除其中的重复数这个办法来实现。

例如先用循环产生一批随机数并存入数据表中，再用

select distinct colName from tableName

选出无重复的随机数予以应用

select distinct(phome_ecms_dp.id), phome_ecms_dp.*,phome_zzz_dianping.* from phome_ecms_dp INNER JOIN phome_zzz_dianping on phome_zzz_dianping.yid=phome_ecms_dp.id where phome_zzz_dianping.shenhe=1 and phome_zzz_dianping.pltitle!='' and length(phome_zzz_dianping.haoping)>30 and length(phome_zzz_dianping.chaping)>30 and length(phome_zzz_dianping.zongjie)>30 ORDER BY phome_ecms_dp.id DESC LIMIT 1 , 20

or

select phome_ecms_dp.*,phome_zzz_dianping.* from phome_ecms_dp INNER JOIN phome_zzz_dianping on phome_zzz_dianping.yid=phome_ecms_dp.id where phome_zzz_dianping.shenhe=1 and phome_zzz_dianping.pltitle!='' and length(phome_zzz_dianping.haoping)>30 and length(phome_zzz_dianping.chaping)>30 and length(phome_zzz_dianping.zongjie)>30 group by phome_ecms_dp.id ORDER BY phome_ecms_dp.id DESC LIMIT 1 , 20

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